Some of those cheap, plastic headphones airplanes give out could have a grisly origin. Both Qantas and British Airways are investigating whether the disposable headphones they distribute on board were made by poorly treated prisoners in a Chinese jail.

According to news.com.au, two inmates came forward to say that they made headphones for Qantas, British Airways and Emirates. The inmates claim that they worked more than 70 hours per week, and if anyone failed to meet production targets, they were “taken outside and tasered.”

All of the airlines have so far denied the charges, but Qantas has suspended arrangements with the company that supplies headphones to the airline, pending an investigation.